Transponder Antenna Location

[Geek]

I have the transponder antenna bracket that Kitfox has and I also know that some of you located the antenna up forward, closer to the landing gear. Pics for reference. I can only find one place where the Kitfox plate really fits and that is farther back in the fuselage. You can see the last joint in the elevator control rods as a reference to where I am finding that plate fits. My question is actually two questions; is where I have the Kitfox plate located really the right place and if not, where should it go? For those who have located the antenna up forward, have you experienced any issues with the landing gear/tires interfering and masking the antenna radiation?

Thanks ahead of time.

Gary

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[PapuaPilot]

I haven't had a problems with my transponder just aft of the landing gear on the pilot's side using the bracket that was welded into the airframe.

[jiott]

Ditto for me.
I think that location farther back is too vulnerable to tall weeds, etc. and of course a longer coax cable run.

[Delta Whisky]

I was able to keep all antennas inside the fuselage and have not experienced any problems.
Antenna locations.jpg

[Geek]

Ditto for me.
I think that location farther back is too vulnerable to tall weeds, etc. and of course a longer coax cable run.

Snapping off that dipole when it was mounted in the back was my thought there as well.

I was able to keep all antennas inside the fuselage and have not experienced any problems.

I gotta admit I like this idea. Going to mull this one over but looks like it might be the best of both worlds.

I haven't had a problems with my transponder just aft of the landing gear on the pilot's side using the bracket that was welded into the airframe.

I keep looking at that plate in relation to the 29 inch behemoth tires and thinking those bad boys are going to cut out a sector of coverage. Good to hear it is working and my worry was wrong.


To all I really appreciate your inputs. So much better to get real world input rather than just guessing at this. Thank you

Gary

[alexM]

I was able to keep all antennas inside the fuselage and have not experienced any problems.
Antenna locations.jpg

Can you provide more pictures or details on that transponder and ADS-B antenna?

I have previously installed a Stratus ESGi transponder in two planes and it used the existing antenna for everything. When I ordered my uAvionics Echo UAT I brushed off the antenna that came with it thinking it was extra. Then I discovered that two very similar looking antennae are normal for everything but the Stratus, and that the antennae have to be at least 36" apart.
My series 5 didn't come with the luxury of all the brackets and tabs most current builders are able to utilize, so seeing this is perfect timing.

[Delta Whisky]

Alex - unfortunately all I have are file pictures in which you can see the antenna/ground plane. I failed to take any to feature them. So, the best I can do is:
ADSB antenna.jpg

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After making the ground planes I made mounting "legs" that placed the gnd planes level when the plane was at a level attitude and the tips of the antennas about 1/4" above where the fabric would be. HTH.

[Eric Page]

Can you provide more pictures or details on that transponder and ADS-B antenna? [...] My series 5 didn't come with the luxury of all the brackets and tabs most current builders are able to utilize, so seeing this is perfect timing.

Alex, if you don't have a sheet of aluminum laying around, here's what I did for transponder and ADS-B ground planes. Home Depot sells small sheets of very thin galvanized steel flashing. It's in the roofing section, near lumber. Very easy to cut to rough shape with shears, a nibbler or a grinder, then fine-tune with a sanding disc or belt. Punch the center hole with a step drill, give it a couple coats of primer, et voila! While at H.D. grab a stick of 3/8" square dowel, which can be cut into pieces and sprayed with varnish to form very lightweight, non-conductive mounts for the ground planes. I used Hysol to adhere the mounting sticks to the frame and the ground planes to the sticks.

The ground planes do not need to be electrically connected to the airframe, but be sure the antennas are electrically connected to the ground planes (remove a small ring of primer where their lock washers make contact).

The transponder (1090 MHz) should be 5.42" diameter and the ADS-B (978 MHz) should be 6.04" diameter. Slightly oversize is fine; don't kill yourself hitting those measurements. If you want to save time, make them square; it'll make no discernable difference in performance.

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[AvDES LLC]

If you’re needing ground plane circles out of aluminum. Drop me a line. I did a big send cut send order and have a few left on my bench. Pay shipping and I’ll send ya as many as you need.

[Delta Whisky]

If you’re needing ground plane circles out of aluminum. Drop me a line. I did a big send cut send order and have a few left on my bench. Pay shipping and I’ll send ya as many as you need.

AvDes - I feel I owe you big time. (Warning - here comes an unpaid advertisement of sorts.) I had not discovered sendcutsend until your above post and wanted to share (in the spirit of this forum) that this is the place to go. As you've read elsewhere, I found parts other than my muffler that needed replacing. I sent 2D files to sendcutsend, they put them in production immediately and shipped in two days. What you see here are 6 parts out of stainless (two shown in the picture are stacks of two), vacuum mounted, and shipped without a separate charge for postage. I did have to pay one whole extra dollar because the 6 parts didn't make their minimum charge - $29.00.

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